Showing papers by "Leibniz University of Hanover published in 1970"
29 Jan 1970
TL;DR: In this article, it was shown that for a plunging breaker the wave energy is dissipated on a very short way (less than on wave length), for a spilling breaker however, this way is of the order of some wave lengths.
Abstract: Even m shallow water, only a part of wave energy is lost by turbulent viscosity and bottom friction, most of wave energy transfer takes place m the narrow zone of surf at the shore. Till to the point of breaking, the theoretical conception of an one-phase flow may be applied to the problem. From beginning of breaking, however, the effect of aeration can not be neglected. Prom a simple physical consideration, the sudden reduction of wave height and wave energy inside the surf zone can be explained by the entrainment of air bubbles into the water. Except compression and surface tension effects, most of wave energy is stored at first by the static energy of the air bubbles which are driven into the water. Using idealized assumptions for calculation (uniform concentration of air bubbles a.s.o.), it can be shown that m a plunging breaker the wave energy is dissipated on a very short way (less than on wave length), for a spilling breaker however, this way is of the order of some wave lengths.
35 citations
29 Nov 1970
TL;DR: In this paper, the effects of thinning and thickening of the profiles on the efficiency, the drop, and the mass flow of multi-stage axial turbines were investigated.
Abstract: When gas and steam turbines are in use, the blade profiles can be thinned by corrosion or erosion and thickened under the influence of deposit formation, thus causing a reduction in efficiency and lifetime. During the production of turbine blades, it is possible that the profiles often become thinner or thicker than the given specified profiles, also causing a decline in efficiency. In addition, the production costs of turbine blades are, to a considerable extent, dependent on the manufacturing tolerances. This report details the effects of thinning and thickening of the profiles on the efficiency, the drop, and the mass flow of multi-stage axial turbines.Copyright © 1970 by ASME
6 citations
TL;DR: In this article, two ways of quantitative treatment of vulcanization processes are developed: one empirical and the other based on the kinetics of consecutive reactions, which possibly give information about the sulfur content of the crosslinks, how to calculate their number, and, in certain circumstances, check the sulfur balance.
Abstract: The preceding treatise describes the vulcanization of 1,5-polyenes as a consecutive reaction based on kinetic investigations. Two ways of quantitative treatment of vulcanization processes are developed: one empirical and the other based on the kinetics of consecutive reactions. The results possibly give information about the sulfur content of the crosslinks, how to calculate their number, and, in certain circumstances, check the sulfur balance. The conditions are discussed which enable the kinetic results to be applied to such applications.
2 citations
24 May 1970
TL;DR: In this paper, the present stage of development of combustion chambers for fossil-fired closed-cycle gas turbines is discussed, describing West Germany's "Gelsenkirchen" plant which can be operated with blast-furnace gas and fuel oil with any desired ratio of gas to oil.
Abstract: The paper discusses the present stage of development of combustion chambers for fossil-fired closed-cycle gas turbines, describing West Germany’s “Gelsenkirchen” plant which can be operated with blast-furnace gas and fuel oil with any desired ratio of gas to oil. The output data and the efficiency of this plant are illustrated by test results. In the development and construction of fossil-fired closed-cycle gas turbine plants, the gas heater presents the greatest difficulties and is the most expensive part of the plant. Therefore, very detailed measurements were taken to determine the total heat absorption in the combustion chamber and its local distribution over the length of the chamber. The results obtained are compared with previous measurements at a smaller plant, the mine-gas and pulverized-coal fired “Haus Aden” plant.Copyright © 1970 by ASME
1 citations
29 Jan 1970
TL;DR: The mixing of salt and fresh water in estuaries of tidal rivers is related to two major phenomenons turbulent diffusion and density currents as discussed by the authors, which can be read off from the horizontal and vertical salinity distribution, and the density current can be determined from the velocity distribution on the vertical axes.
Abstract: The mixing of salt and fresh water in estuaries of tidal rivers is related to two major phenomenons turbulent diffusion and density currents The turbulent diffusion can be read off from the horizontal and vertical salinity distribution, the density current can be determined from the velocity distribution on the vertical axes The physical description of tidal mixing in a mathematically closed system is not possible, because turbulent diffusion and gravitational convection are varied by such different influences as tidal action, fresh water flow, river bed form and roughnes, and gravitational and CORIOLIS forces Most research in this field has been done on turbulent diffusion, especially to predict the mean horizontal (longitudinal) salinity distribution IPPEN, HARLEMAN (ref 11, 12), and others have found out by various model tests that PICK'S law of diffusion used in one-dimensional form is a good physical description for the longitudinal salinity distribution and that the tidal energy dissipation, the cross section, and the fresh water flow are a good means of classifying tidal estuaries from the viewpoint of stratification.